Process of sulphonating mineral oil



and other known and used processes.

Patented Sept. 22, 1931 UNITED STATES PATENT OFFICE LATIMER D. MYERS, OF CINCINNATI, OHIO, ASSIGNOR TO THE PROCESS COMPANY, OF ST. BERNARD, OHIO, A CORPORATION Olf' OHIO PROCESS OF SULPHONATING MINERAL OIL No Drawing.

This invention relates to a process of treating mineral oil to produce medicinal white oil or the light colored technical oils and mineral oil sulphonates.

Specifically, this invention is directed to a process which is an improvement over the process disclosed in Petroif Patent No. 1,087,- 888, issued February 19, 1914, Humphrey Patent N 0. 1,286,179, issued November 26, 12218,

ccording to the above specified patents mineral oil such as a lubricating stock is treated with fuming sulphuric acid repeatedly. After each treatment, the sludge is drawn off and after repeated treatments mahogany sulphonates are extracted from the oil layer leaving a remainder of relatively clear oil or white oil, and water soluble sulphonates are extracted from the sludge layer. The prod. nets of these processes are, therefore, white oil, mahogany sulphonates, or oil soluble sulphonates, and water soluble sulphonates. The mahogany sulphonates have been used for many years past as saponifiers in the soap,

stearic acid and glycerine producing industries. The sludge layer sulphonates are at present extensively used for decomposing or resolving the petroleum and water emulsionsencountered in the oil fields. Other uses for these sulphonates are developing and they are becoming of increasing commercial importance.

So far the refining operations have been carried on solely from the point of view of producing white oil, and the sulphonates have been treated as inconsequential by-products.

The present inventors have, however, inves tigated the refining operations with the view of altering and adjusting them to produce greater yields of the sulphonateswithout 1nterfering with the yield of white 011, and without increasing the cost of the operation out of proportion to the benefit obtained.

It has been recognized in the past that frequent extractions of the sulphonates from the oil layer, as distinguished from a single extraction at the end of the sulphonating treatment, augments the yield of oil layer sulphonates. This, however, increases the cost of the operation very materially. The inventors Application filed March 2, 1929. Serial No. 844,100.

have, therefore, investigated the character and strength of the acid to be used and also the temperature at which the sulphonation is carried on with the view of obtaining higher yields of the sulphonates without extracting them from the oil .layer oftener than every second or third sulphonation. In eneral, experiments show that increase in t e strength of the fuming sulphuric acid results in greater production of mahogany sulphonates, but also results in greater destruction of the mahogany sulphonates upon second treatment wit-h the'fuming acid. Sulphonating at elevated temperatures increases the yield of mahogany acids and does not bring about any greater decomposition of the mahogany acids on the second treatment with fuming sulphuric acid, but the use of too high a temperature results in the coking of the sludge sulphonates which renders them worthless.

The problem of the inventors was, therefore, to determine the strength and type acid and the temperature most expedient for producing a high yield and a desirable balance of mahogany sulphonates-and sludge sulphonates without requiring too frequent extraction of the maho any sulphonates from the oil layer. The ollowing example is therefore given to illustrate this invention, though it must be understood that minor departures can be made from the exact temperatures and acid strengths specified without sacrificing the novel increment of yield of sulphonates.

A high gravity petroleum distillate such as a heavy lubricating stock, preferably from a naphthenic or a mixed base crude oil, is treated with 5% its weight of concentrated sulphuric acid after which the oil is allowed to stand until the asphaltic and resinous materials contained in the oil have precipitated. This requires from three to four hours on a low gravity oil, and up to twenty-four hours on a heavy viscous oil. celerated by maintaining the oil at a temperature such as 50 C. The oil is then separated from the material which settled out, and its surface is sprayed with fuming sulphuric acid. During this spraying operation, the oil is preferably agitated either by. dry air or by mechanical devices. This "fuming sul- The settling is acphuric acid contains between 25 and or preferably 30%, free SO as this concentration of oleum has been found to give the greatest yield of mahogany sulphonates based on available S0 used and does not cause excessive decomposition of the mahogany acids on the second treatment.

For any single "sulphonation treatment approximately 20% of fuming sul huric acid is used, the 20% being based on t e weight of the oil treated. During this sulphonation the oil is held in most cases at a temperature between 50 and 60 C. This has been found to be the maximum temperature that can be employed for most oils. Although sulphonation at a higher tem erature results in an increased yield of ma ogany acids the sludge acids are reduced to coke. The fumin sulphuric acid is added as rapidl as consistent with the conservation of the su phur trioxide,

though care must be taken that the heat de-' great as to.

veloped by the reaction be not so coke some of the material.

After the fuming sulphuric acid has been added, the oil is allowed to stand until the sludge has completely precipitated. A temperature such as 50 (1. is suitable for the settling. The sludge is then drawn off and the oil is subjected to a second sulphonation similar to the one 'ust described. After the second sludge has een drawn off, the oil is thoroughly mixed with 50% of its weightvof 66% strength aqueous methyl alcohol, and sufilcient sodium carbonate or an equivalent amount of-some other alkali to neutralize the mineral oil sul honic acids and free sulphuric acid containe in the oil. The aqueous alcohol dissolves these sulphonates since they are preferentially soluble in it.

Other alcohols and water mixable organic solvents can housed in place of the alcohol specified. The aqueous alcohol containing the dissolved sulphonates and the oil are then allowed to separate by gravity or are run through a centrifuge. The latter is recommended as it effects a more complete separation of the oil and sulphonates since there is a physical attraction between particles of the oil and the sulphonates which is not comsludge sulphonates is not materially afiected.

Havin described my invention, I desire to be limited only by the ensuing claims:

1. In the process of producin white oil or light colored technical oils, ma ogany sulphonates, and sludge layer sulphonates from mineral oil, the step of sulphonating said oil with a fuming sulphuric acid containing between'25 and 35% free sulphur trioxide at a temperature of between 50 and 60 C.

2. In the process of producing white oil or light colored technical oils, mahogany sulphonates, and sludge layer sulphonates from mineral oil, the step of treating said mineral oil with fuming sulphuric acid containing between 25 and 35% free sulphur trioxide.

In witness whereof, I hereunto subscribe pletely overcome by the force of gravity, but i can be overcome in the centrifuge. The oil' is then subjected to further sulphonations, settlings, and. extractions as outlined above, and this treatment is continued until the oil after extraction is sufiiciently light in color for the purposes required. The sludge sulphonates are extracted by various methods known to the art.

When the process described above is followed, the yield of valuable mahogany sulphonates is very much higher than the yield provided by following the disclosure of either the Petrofi' or Humphrey patents above enumerated, and the y1eld of the also useful 

